Research On Modular Design Of Embankment Technology In Permafrost Regions

With the intense temperature change of the permafrost,the permafrost subgrade will experience complicated deformation process,resulting in great harm to the stability of the permafrost subgrade.Due to the restriction of the insufficiency in the theories,experiments,test means and the numerical models at present,there is lack of sufficient and reliable theoretical basis for the subgrade design methods with the existing permafrost subgrade long-term deformation prediction and control of subgrade deformation as the core task.And it is an urgent problem to be solved on decision-making for the design of the highway subgrade within the permafrost area.In view of this problem,the permafrost subgrade engineering deformation model is established through theoretical analysis in this thesis,numerical calculation is applied to evaluate the stability of the permafrost subgrade slope,and on the basis of the research on the deformation stability and strength stability of permafrost subgrade,permafrost subgrade modular classification design method is proposed:(1)The influence factors on the permafrost subgrade deformation and the main components are analyzed,the permafrost subgrade engineering deformation computation model is put forward,and through the observation of the melting disc morphology of the permafrost subgrade and the upper limit variation law,the computational formula of the prediction on the upper limit of the permafrost subgrade changes is derived.It is considered that the artificial upper limit of the permafrost subgrade is closely related to the subgrade height,road operating time and annual mean ground temperature.It is also proposed that the melt settlement deformation of the permafrost subgrade is the major component of the deformation of permafrost subgrade,and thus the design height computational formula based on the permafrost subgrade deformation theory is obtained.(2)The stability of the permafrost subgrade slope under different working conditions is evaluated through the application of two improved limit equilibrium methods,namely,the polygon method and arc method,and the monthly variation characteristics of the permafrost subgrade slope stability is obtained.The influence of the subgrade height,subgrade slope,berm and pavement width on the stability of the permafrost subgrade is analyzed,and the lower critical height key parameters of the permafrost subgrade on the basis of the subgrade strength stability are put forward.(3)The subgrade settlement deformation is classified based on the pavement stress distribution,which is divided into three grades of "Light","Medium","Heavy" according to the different influence of the settlement on the pavement cracking.According to the settlement deformation of the permafrost subgrade and its influence on pavement performance,different melt settlement coefficients and average annual temperature on the subgrade settlement,the subgrade design theoretical height under different working conditions are determined,and based on the comparison of the critical height of subgrade strength stability,the reasonable height of the subgrade at the permafrost area is determined accordingly.